The objectives of the Environmental Mutagenesis Test Development Program are twofold. The first is the development of an integrated program for the routine testing of large numbers of chemicals for mutagenicity. This includes such diverse factors as test-system validation, identification and development of new test methods, development of an increased understanding of mutagenesis and development of a strategy and an organizational structure for conducting a large scale testing program and interpreting the results obtained. The second objective is implementation: to test up to 1000 commercial and environmental chemicals per year for mutagenicity.